Early childhood education (ECE) is widely recognized as crucial for children's cognitive, social, and emotional development, laying a foundation for future academic success and overall well-being. Neuroscience supports the idea that the early years are a period of heightened learning capacity. Research consistently demonstrates that enriched learning environments positively influence cognitive abilities. While ECE's primary goal is to maximize cognitive development and prepare children for school, its historical focus has shifted from childcare to a distinct educational field with varying structures and approaches across countries. ECE also plays a critical role in promoting educational equity, mitigating achievement gaps, particularly among disadvantaged students, by providing equal learning opportunities. In Turkey, where achievement gaps have been a long-standing issue, ECE's potential for reducing these disparities is significant, particularly given that the socioeconomic gap between students is apparent before formal schooling begins. Studies have shown that ECE interventions cannot be compensated for by later investments, highlighting their importance for long-term development and reduced costs associated with underachievement. Despite the widespread support for ECE, its implementation and universalization face barriers and disparities globally, including in Turkey, where participation rates have been historically low compared to other OECD countries. This study addresses the need for further evidence on the relationship between ECE attendance and academic performance in Turkey over the medium and long term.

Extensive research exists on the link between ECE attendance and educational outcomes. Studies like Barnett (1995), Currie and Thomas (1995), Gorey (2001), Campbell et al. (2002), Reynolds et al. (2003), and Schweinhart et al. (2005) demonstrate positive correlations between ECE participation and improved cognitive skills, academic achievement, higher education attainment, and increased lifetime earnings, particularly for disadvantaged children. However, some studies, such as Gupta and Simonsen (2015) and Nold et al. (2021), have found either insignificant or weaker relationships over time, highlighting the complexity of this relationship and the need for further research considering factors like program structure, curriculum, and duration. The Turkish context presents unique challenges; while ECE's history in Turkey dates back to the Ottoman Empire, its widespread adoption is relatively recent, leading to limited research on its long-term impacts compared to countries with established systems. Existing Turkish studies often have methodological limitations, including small sample sizes and limited socioeconomic analyses.

This causal-comparative ex post facto study utilized data from the Turkish Ministry of National Education (MoNE) on 5,625,798 students who took higher education entrance exams between 2018 and 2021. The study population included both ECE attendees and non-attendees. Demographic data collected included gender, parents' education levels, and family income, used to determine socioeconomic status (SES). Academic achievement was measured using scores from the High School Transition System (LGS) exam (medium-term, taken around 8th grade) and the Basic Proficiency Test (TYT) and Field Proficiency Test (AYT) exams (long-term, taken around 12th grade). The LGS, TYT, and AYT assessments exhibit high reliability and validity. One-way ANOVA was employed to compare mean scores between ECE attendees and non-attendees for each assessment, with partial-eta squared used to measure effect sizes. Long-term outcomes also included higher education placement rates, focusing on prestigious programs and students' program preferences. SES was categorized into low, medium, and high based on a cumulative frequency analysis of a composite SES score derived from parental education and family income. Descriptive comparisons were made to examine the relationship between ECE attendance and long-term educational indicators across different SES levels.

Students who attended ECE scored significantly higher on the LGS exam (transition to upper-secondary education), indicating a strong, though modest, medium-term effect (partial η² = 0.03). The effect size was smaller for the TYT and AYT exams (long-term, transition to higher education), with statistically significant but small effects (partial η² ≤ 0.01). While the overall transition rates to higher education were similar between ECE attendees and non-attendees, ECE attendance was significantly associated with higher rates of placement in prestigious higher education programs. ECE attendees also showed a higher likelihood of being placed in their top five program preferences. Analysis by SES revealed a stronger positive effect of ECE on academic achievement for students from low and medium SES groups, particularly in the transition to upper secondary education. For these groups, ECE participation helped to reduce the gap between their scores and the overall mean score. The effect was less pronounced at the higher education level.

This study provides strong evidence for the medium- and long-term benefits of ECE in Turkey, particularly for disadvantaged students. The findings align with international research emphasizing the positive impact of ECE on academic achievement and equity. The stronger medium-term effect may reflect the cumulative effects of ECE on foundational skills influencing subsequent performance. The less pronounced long-term effects may be due to the complex interplay of factors influencing higher education success beyond early childhood experiences. The significant association between ECE and placement in prestigious programs suggests that ECE helps students develop the skills and motivation for achieving competitive higher education outcomes. The differential effects based on SES underscore the importance of targeted ECE interventions for disadvantaged populations in addressing persistent educational inequalities in Turkey. This is particularly relevant in a country where a high percentage of students are from socioeconomically disadvantaged backgrounds.

This large-scale study confirms the positive medium- and long-term impacts of ECE on academic achievement in Turkey. The findings highlight the importance of continued investment in ECE, especially for students from low SES backgrounds to reduce achievement gaps. Future research should investigate the specific aspects of ECE programs that contribute to these outcomes, examine the long-term impacts beyond formal education, and explore the role of family and community factors in mediating the relationship between ECE attendance and achievement.

While the study's large sample size enhances generalizability, its focus on students who took university entrance exams between 2018 and 2020 limits its scope. The study didn't account for the type or duration of ECE programs, which could influence outcomes. SES was based on a limited set of variables, potentially underrepresenting the complexity of socioeconomic factors. Finally, the study did not consider non-registered students or other educational pathways.